The invention relates to a method of producing an electronic device, with a stamped sheet-metal part loaded with electronic components being encapsulated in a thermoplastic, insulating material to provide protection from environmental influences, and to an electronic device comprising electronic components arranged on a stamped sheet-metal part and electrically connected to one another by said part, the stamped sheet-metal part and the electronic components being encapsulated in a thermoplastic, insulating material by the injection-molding process.
To provide protection from environmental influences, electronic circuits are usually completely sheathed in plastic. A method of encapsulating electronic circuits in insulating material is known from German laid-open patent application DE 44 36 523 A1. Here, before being loaded with electronic components, a conductor part is encapsulated in an electrically insulating material in such a way that clearances remain in the encapsulation on the conductor part for positioning and connecting the electronic components. Subsequently, the loading with electronic components and their welding take place. After that, the partly encapsulated conductor part is placed into an injection mold for encapsulating in the material forming a housing of an electronic device.
An electronic device produced in this way is used for example as a sensor operated in a motor vehicle. Sensors used in motor vehicles are exposed to very adverse environmental conditions. ABS sensors, for example, must endure heavy soiling, withstand considerable temperature fluctuations, at the same time operate extremely reliably and be very durable. This can only be ensured if the sensor and the electronics required in its direct vicinity are sheathed in at least one high-grade protective layer.
It has proven to be inexpensive and advantageous from a process engineering aspect to mount the sensor and the electronics required in its direct vicinity completely on a stamped sheet-metal part. The metallic stamped sheet-metal part is in this case used both for the electrical contacting of the electronic components and for the mechanical fixing of the components in the desired position. The electronic components are mechanically and electrically connected to the stamped sheet-metal part by soldering or welding. The subassembly prepared in this way is inserted into a prefabricated lower housing part and then placed into an injection mold for producing the upper housing half. The upper housing half is produced by injection-molding with the electrically insulating material.
During the encapsulation of the electronic components, a very high injection pressure is transferred to them and they are subjected to a very high temperature, which is passed on to the components from the insulating material injected in a heated state, which can lead to individual electronic components being damaged or destroyed, making the entire subassembly worthless.
The invention is therefore based on the object of providing a method and a device with which protection of the electronic components during encapsulation is ensured.